1. Field of the Invention
The present invention generally relates to a contactor for electronic parts and, more particularly, to a contactor for electronic parts which contactor provides electrical conduction by contacting an electrode of a semiconductor device, such as an LSI circuit, to test the semiconductor device, and to a testing method using such a contactor.
Recently, a manufacturing technology of a semiconductor substrate and the like has been remarkably developed. Accordingly, a wiring pattern of a semiconductor device, such as an LSI circuit, has become finer, and terminals have been remarkably increased in number and miniaturized.
Also, miniaturization and high-density packaging are required for an electronic device using the semiconductor devices. For example, production and sales of mobile devices, such as a cellular phone, a mobile PC and a video camera, which are required to be small and of high performance are sharply increasing. Also, a need for a highly efficient computer having a minimum distance between adjacent LSI terminals to ensure a high-speed operation is increasing.
Therefore, more and more semiconductor devices such as the LSI circuit are shipped in the form of an unpackaged LSI chip with its function guaranteed. Such a shipping is referred to as a KGD (Known Good Die). Also, a number of shipping chip-size-packages (CSP), which are semiconductor devices packaged in the same size as the LSI chip, is sharply increasing.
In these circumstances, in order to conduct a test for the semiconductor devices such as the LSI circuit, a supply of a contactor capable of surely conducting electrically with a multitude of terminals formed as a part of the finer wiring pattern is becoming essential.
Also, from the viewpoint of efficiency in LSI tests, there is an ever-increasing need to conduct all of tests, such as an FT (Final Test) and a BI (Burn-In test), for a plurality of LSIs in the form of a wafer formed in an LSI manufacturing process.
A full test in the form of a wafer has an advantage of better handling efficiency than testing a separate LSI chip. That is, if each chip has a different size, a handling facility cannot be used commonly. However, in the form of a wafer, since the external shape of the wafers is standardized, the wafers can be conveyed all at once. There is also an advantage that information of inferior chips can be administered with a wafer map.
Further, for a wafer-level CSP which has recently been developed, even a packaging process can be controlled by the unit of a wafer. Therefore, if a test in the form of a wafer can be realized, LSI circuits can be treated in the form of a wafer from a wafer process through the packaging process to the tests. This makes the LSI manufacturing process efficient.
Hence, it is desired, as mentioned above, that a contactor capable of contacting a plurality of terminals of LSI circuits all at once be developed, the LSI circuits being in the form of wafer and having a multitude of miniaturized pins.
2. Description of the Related Art
Conventional contactors used for testing LSI circuits include: 1) a contactor using a mechanical probe of a needle type; 2) a contactor using a membrane probe; and 3) a contactor using an anisotropic conductive rubber.
1) A contactor using a mechanical probe of a needle type:
The contactor using a mechanical probe of a needle type is formed by placing each of needles (formed of such a material as a tungsten wire) at a position on a contactor substrate, the position corresponding to a terminal of an LSI circuit to be tested. Generally, each of the needles is slant from upright, extending toward the terminal of the LSI circuit. However, a method whereby each of the needles is placed upright has been developed.
2) A contactor using a membrane probe:
The contactor using a membrane probe is formed as a circuit substrate in the form of a film, the circuit substrate having a metal protrusion (referred to as a bump hereinafter) as a contact electrode for use as a stylus.
3) A contactor using an anisotropic conductive rubber:
The contactor using an anisotropic conductive rubber is formed of a rubber as an insulating member and a material (such as a metal wire) embedded therein, the material being conductive only in a thickness direction (perpendicular direction).
1) The contactor using a mechanical probe of a needle type has the following problems:
a) A manufacturing cost of the contactor is high, because the needles are formed one by one.
b) A location precision is subject to a limit, because the needles are individually mounted on the contactor substrate.
c) In a case of forming each of the needles to be slant, an arrangement of the needles is subject to a limit. Thus, it is difficult to manufacture the contactor capable of contacting a plurality of LSI circuits all at once.
2) The contactor using a membrane probe has the following problems:
a) Each of the contact electrodes cannot move freely. Since each of the contact electrodes is embedded in an insulating substrate, each of the contact electrodes can move only within a small range. Also, because the contact electrode is a metal bump, the contact electrode lacks flexibility. Therefore, when adjacent bumps have different heights, the lower bump does not contact the corresponding terminal or causes a poor connection.
b) Since the bump as a contact electrode is generally formed by laminating metal plating layers, manufacturing the bump takes a long time and the bump cost is high.
3) The contactor using an anisotropic conductive rubber has the following problems:
a) The contactor using an anisotropic conductive rubber has a short life duration. Especially, when used at a high temperature, the rubber part undergoes plastic deformation. Therefore, the contactor using an anisotropic conductive rubber can only be used 20 to 30 times at best and only once at worst.
b) Since it is difficult to embed the conductive materials with a fine pitch into the rubber, the contactor using an anisotropic conductive rubber cannot be used to test an LSI circuit having terminals with a fine pitch. This contactor can only be used to test an LSI circuit having terminals with approximately a 150 xcexcm or greater pitch.
Further, in a case of using a contactor to test wafer-level LSI circuits all at once, a number of terminals of the LSI circuits sometimes totals several tens of thousands (100,000 terminals). Thus, the above-mentioned contactors commonly have the following problems.
I) A great pressure is required to press the contactor against the terminals of the LSI circuits.
With the above-mentioned conventional contactors, a pressure of 0.1 N (approximately 10 grams) a terminal is required. Therefore, in a case where a wafer has 100,000 terminals, a pressure of 10,000 N (approximately 1,000 kilograms) is required. With the conventional contactors, because of the different heights of the electrodes and other reasons, it is difficult to impose a pressure on all of the terminals uniformly. Thus, an excessive pressure is sometimes imposed on particular terminals. Additionally, without a facility that accepts all the pressure, there is a risk that the wafer may be broken or bent so that a circuit on the LSI chip is damaged.
II) Different coefficients of thermal expansion cause undesired shifting.
In most cases, a wafer for LSI circuits is made of silicon. A coefficient of linear expansion thereof is approximately 3 ppm. On the other hand, the insulating substrate of each of the above-mentioned contactors is formed of a resin or a rubber material, and a coefficient of linear expansion thereof is approximately 13-30 ppm. Therefore, even though the contactor accurately contacts the terminals of the LSI circuits at a normal temperature, when put at a high temperature as in the BI test, there is a risk that different coefficients of thermal expansion between the material forming the insulating substrate of the contactor and the silicon material of the wafer cause the contact electrode to shift so that the contact electrode is detached from the corresponding terminal of the LSI circuit or contacts an adjacent terminal. In a case where the insulating substrate of the contactor is formed of polyimide, a coefficient of thermal expansion of the polyimide is approximately 13 ppm. Thus, even though the contactor accurately contacts the terminals of the LSI circuits at a normal temperature, when heated to a temperature of 125xc2x0 C., the contactor electrode is shifted from the corresponding terminal by as much as 100 xcexcm around the outermost periphery, when using an 8-inch wafer (approximately 100 mm in diameter).
It is a general object of the present invention to provide an improved and useful contactor for testing electronic parts, in which contactor the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide a contactor which has contact electrodes capable of undergoing large elastic deformation in a thickness direction (perpendicular direction) though formed with a narrow pitch and which contactor can contact all of the contact electrodes with terminals of semiconductor devices with a low pressure even when the contact electrodes have different heights.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a contactor comprising:
an insulating substrate;
a concave portion formed in the insulating substrate and extending in a perpendicular direction from a surface thereof; and
a plurality of conductive particles having elasticity and disposed in the concave portion, a part of one of the conductive particles protruding from the surface of the insulating substrate.
According to the present invention, the part of the conductive particle protruding from the surface of the insulating substrate functions as a contact electrode. A plurality of the conductive particles are disposed in the concave portion of the insulating substrate. Each of the conductive particles undergoes elastic deformation so as to produce a contact pressure of the contact electrode. Each of the conductive particles contacts and conducts with each other. Around the conductive particles in the concave portion is a space in which the conductive particles can deform.
Accordingly, each of the conductive particles can deform freely, and as a result, when a terminal of an object to be tested is pressed against the protruding conductive particle so that the protruding part thereof becomes flat, each of the conductive particles can deform while maintaining a considerably low pressure. Therefore, even in a case of a multitude of terminals as in a wafer-level semiconductor device test, a low pressure can provide a sure contact.
Additionally, in the contactor according to the present invention, the concave portion may be formed as a through hole penetrating through the insulating substrate in the perpendicular direction, and parts of the conductive particles on both ends of the through hole protrude from both surfaces of the insulating substrate, respectively.
According to the present invention, by aligning the conductive particles in the through hole and arranging the conductive particles on both ends to protrude from both surfaces of the insulating substrate, the contactor having the contact electrodes on both surfaces of the insulating substrate can be achieved. This structure is very simple and thus can be manufactured at a low cost.
Additionally, in the contactor according to the present invention, the concave portion may be formed as a through hole penetrating through the insulating substrate in the perpendicular direction, and a terminal for circuit wiring closes one end of the through hole.
According to the present invention, since the terminal for circuit wiring is formed on one end of the through hole, a column of the conductive particles electrically connects a tip of the contact electrode and the terminal for circuit wiring. In addition, since the conductive particles produce a contact pressure, the contact electrode can have a very simple structure.
In order to achieve the above-mentioned objects, there is also provided according to another aspect of the present invention a contactor comprising:
an insulating substrate;
a concave portion formed in the insulating substrate and extending in a perpendicular direction from a surface thereof;
a conductive liquid filling the concave portion; and
a conductive particle disposed in the concave portion and having a specific gravity different from a specific gravity of the conductive liquid,
wherein a difference between the specific gravity of the conductive particle and the specific gravity of the conductive liquid causes a part of the conductive particle to protrude from a surface of the insulating substrate.
Additionally, in the contactor according to the present invention, the specific gravity of the conductive particle may be smaller than the specific gravity of the conductive liquid so that a buoyancy acting on the conductive particle causes the conductive particle to protrude from the insulating substrate.
Additionally, in the contactor according to the present invention, the specific gravity of the conductive particle may be higher than the specific gravity of the conductive liquid so that a gravity force acting on the conductive particle causes the conductive particle to protrude from the insulating substrate.
According to the present invention, a difference in specific gravities between the conductive particle and the conductive liquid causes a buoyancy or a gravity force, and thus produces a contact pressure. Therefore, such a simple structure as this can provide an extremely low contact pressure.
In order to achieve the above-mentioned objects, there is also provided according to another aspect of the present invention a contactor comprising:
an insulating substrate;
a concave portion formed in the insulating substrate and extending in a perpendicular direction from a surface thereof;
a plurality of conductive particles disposed in the concave portion, the conductive particles being aligned with each other in a direction in which the concave portion extends, and being contacted with each other;
an insulating film formed on the surface of the insulating substrate; and
a conductive portion formed at a position of the insulating film corresponding to an opening of the concave portion,
wherein a coefficient of linear expansion of each of the conductive particles is larger than a coefficient of linear expansion of the insulating substrate, and when the contactor is heated, each of the conductive particles undergoes thermal expansion so that the conductive portion protrudes by being pressed by the conductive particles.
According to the present invention, the conductive particles undergo thermal expansion at an operating temperature so that the conductive portion formed in the insulating film protrudes. This protruding conductive portion can be used as the contact electrode.
In order to achieve the above-mentioned objects, there is also provided according to another aspect of the present invention a contactor comprising:
an insulating substrate;
a concave portion formed in the insulating substrate and extending in a perpendicular direction from a surface thereof;
a conductive liquid filling the concave portion;
a conductive particle mixed in the conductive liquid;
an insulating film formed on the surface of the insulating substrate; and
a conductive portion formed at a position of the insulating film corresponding to an opening of the concave portion,
wherein, when the contactor is heated, the conductive particle mixed in the conductive liquid undergoes thermal expansion so that the conductive portion protrudes by being pressed by the conductive particle mixed in the conductive liquid.
According to the present invention, a mixture of the conductive particle and the conductive liquid undergoes a larger thermal expansion than an increase in volume of the concave portion caused by thermal expansion of the insulating substrate. Therefore, in a case of conducting a test at a heated temperature, the thermal expansion of the mixture causes the conductive portion of the insulating film to protrude. This protrusion enables a proper contact.
In order to achieve the above-mentioned objects, there is also provided according to another aspect of the present invention a test method using a contactor comprising an insulating substrate; a concave portion formed in the insulating substrate and extending in a perpendicular direction from a surface thereof; and a plurality of conductive particles having elasticity and disposed in the concave portion, a part of one of the conductive particles protruding from the surface of the insulating substrate, the method comprising the steps of:
placing an object to be tested opposite to the contactor so that an external connection terminal of the object to be tested is aligned with the part of one of the conductive particles protruding from the surface of the insulating substrate; and
pressing the contactor against the object to be tested so that a surface of the object to be tested contacts the surface of the insulating substrate with a predetermined low pressure.
According to the present invention, simply pressing the contactor against the object to be tested can have the contactor contact the object to be tested with a proper contact pressure. Since each of the conductive particles can undergo elastic deformation easily, an extremely low contact pressure can be achieved. For example, when the contactor is used in testing a semiconductor device in the form of a wafer, a low pressure can provide a sure contact.
In order to achieve the above-mentioned objects, there is also provided according to another aspect of the present invention a test method using a contactor comprising an insulating substrate; a concave portion formed as a through hole penetrating through the insulating substrate in a perpendicular direction; and a plurality of conductive particles having elasticity and disposed in the concave portion, parts of the conductive particles on both ends of the through hole protruding from both surfaces of the insulating substrate, respectively, the method comprising the steps of:
placing a test substrate opposite to one surface of the contactor so that a connection terminal of the test substrate contacts a part of the conductive particles at one end of the through hole protruding from one surface of the insulating substrate;
placing an object to be tested opposite to the other surface of the contactor so that an external connection terminal of the object to be tested contacts a part of the conductive particles at the other end of the through hole protruding from the other surface of the insulating substrate; and
pressing the test substrate and the object to be tested against the contactor with a predetermined low pressure so that the test substrate and the object to be tested contact the contactor and electrically connect to each other.
According to the present invention, simply placing the contactor between the test substrate and the object to be tested and pressing the test substrate and the object to be tested against the contactor can achieve a sure contact with a low contact pressure.
In order to achieve the above-mentioned objects, there is also provided according to another aspect of the present invention a contactor comprising:
an insulating substrate;
a concave portion formed in the insulating substrate and extending in a perpendicular direction from a surface thereof; and
a conductor disposed in the concave portion, the conductor being in either a liquid phase or an intermediate phase between a liquid phase and a solid phase at an operating temperature,
wherein a part of the conductor protrudes from the surface of the insulating substrate, the part formed as a protrusion.
According to the present invention, since the conductor comes in either a liquid phase or an intermediate phase between a liquid phase and a solid phase at an operating temperature, a very low pressure can deform the conductor. Therefore, when using the protrusion of the conductor as the contact electrode, an electrical contact with a substantially zero contact pressure can be achieved.
In order to achieve the above-mentioned objects, there is also provided according to another aspect of the present invention a test method using a contactor comprising an insulating substrate; a concave portion formed in the insulating substrate and extending in a perpendicular direction from a surface thereof; and a conductor disposed in the concave portion, the conductor being in either a liquid phase or an intermediate phase between a liquid phase and a solid phase at an operating temperature, in which contactor a part of the conductor protrudes from the surface of the insulating substrate, the part formed as a protrusion, the method comprising the steps of:
placing an object to be tested opposite to the contactor so that an external connection terminal of the object to be tested is aligned with the protrusion; and
pressing the contactor against the object to be tested so that a surface of the object to be tested contacts the surface of the insulating substrate with a predetermined low pressure.
According to the present invention, simply having the contactor adjoin the object to be tested can have the contactor contact the object to be tested with substantially no pressure. Therefore, when the contactor is used in testing a semiconductor device in the form of a wafer, a low pressure can provide a sure contact.